Resonant optical cavities in combination with quantum optical emitters have been under investigation for some time for various applications, such as switching and information processing. Photonic crystals (PCs) are a promising platform for implementing such structures. For example, in US 2008/0101800, dipole induced transparency of a PC resonant cavity coupled to a quantum dot (QD) is exploited to provide switching in the weak coupling, bad-cavity limit. Another example is considered in U.S. Pat. No. 7,031,585, where a PC atom-cavity system exhibits large nonlinear effects due to electromagnetic induced transparency.
Devices based on this technology often require an external control input to be provided to the emitter (e.g., atom or quantum dot) to control device operation. For example, the device transmittance from an optical input port to an optical output port can be altered by varying the control input, which can provide device functionality such as switching. However, it is critical that the control input be provided such that cavity and emitter losses are not significantly and undesirably increased. The reason for this is that coupled emitter-cavity devices typically rely on having low losses in order to provide the desired functionality.
This requirement of low loss significantly limits the possibilities for providing the control input. One approach that has been demonstrated is to provide the control input as an optical signal. Although this approach can provide low loss, it is not applicable in all situations.
Accordingly, it would be an advance in the art to provide coupled emitter-cavity devices that have an improved capability of controlling the emitter.